This application claims the priority of German Application No. 199 26 246.2 filed Jun. 9, 1999.
This invention relates to a method of internally coating at least one portion of the inner surface of a weapon barrel with at least one layer for preventing erosion.
In weaponry, efficiency-augmented ammunition causes significant erosions, particularly in steel weapon barrels, due to the high gas temperature and flow velocities generated during firing. Such erosions wear out the barrel even before service-terminating metal fatigue sets in. It has been known to provide the inner surface of weapon barrels with a hard chromium layer to prevent such erosions. Conventionally, the hard chromium is electrolytically deposited on the inner surface of the weapon barrel.
It is a disadvantage of the above-outlined conventional method that, among others, the electrolytically deposited hard chromium layers do not satisfactorily withstand the effect of efficiency-augmented ammunition. Thus, significant erosion phenomena appear at inner barrel areas which consequently lose the chromium coating.
It is an object of the invention to provide an improved method of coating an inner surface of a weapon barrel with which high melting point layers may be applied to the inner surface of the weapon barrel for preventing erosion and wherein such layer or layers particularly excel in a high degree of adherence.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the method of coating an inner face of a weapon barrel with a coating material includes the following steps: introducing the coating material as a component in sheet or foil form into the weapon barrel; positioning the component in the weapon barrel such that a first face of the component is oriented toward the inner face of the barrel and a second face of the component is oriented away from the inner face of the barrel; maintaining an annular clearance between the inner face of the barrel and the component; providing the second face of the component with an explosive; and detonating the explosive for hurling the coating material of the component against the inner face of the barrel for effecting a cold welding between the coating material and the inner face of the barrel.
The invention is essentially based on the principle to coat the inner surface of the weapon barrel by explosive plating. In this method, a sheet or foil of the coating material is provided with an explosive substance and is introduced into the weapon barrel in such manner that between the inner surface of the barrel to be coated and the sheet or foil a clearance is maintained. Thus, upon ignition of the explosive the coating material is hurled against the inner face of the barrel and is fused therewith by xe2x80x9ccoldxe2x80x9d welding.
It is a significant advantage of the method according to the invention that high-melting point substances such as niobium, molybdenum, tantalum, hafnium, vanadium, tungsten, zirconium or their alloys may be applied to the inner surface of the weapon barrel in layer thicknesses from a few tenths of a millimeter up to a few millimeters without the effect of a metallurgical exchange between the substances. Consequently, bonds between the weapon barrel and the respective substance are feasible which are not soluble in one another, which form intermetallic phases at high temperatures or which have substantially different melting points.
Advantageously, when performing the method according to the invention, no melting of the barrel material and thus no alloy formation between the barrel material and the coating material takes place. Further, underneath the coating material a heat influx zone is formed. In addition, the explosive plating process offers the possibility to apply a plurality of layers in a simple manner without the individual layers having a mutual metallurgical effect on one another.
The coating material may be applied either to the entire inner surface of the weapon barrel or to selective zones thereof. In either case care has to be taken that the weapon barrel is, before the coating operation, adapted to a suitable wall thickness of the coating material to be applied. Stated differently, the barrel portion to be coated must have a diameter which corresponds to the caliber diameter plus twice the thickness of the layer to be applied.
In accordance with an advantageous feature of the invention, the sheet or foil constituted by the coating material is provided with cutouts which form spacers after the introduction of the sheet or foil into the weapon barrel.
In accordance with a further embodiment of the invention, the sheet or foil part surrounds a cylindrical body. Between the cylindrical body and the sheet or foil part an intermediate space remains into which an explosive (preferably a powder) is introduced.